Steel Member Bonding with Metal Plating and Acid Etching
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Solution Overview
Problem
Existing methods for bonding steel members with thermoplastic resins, such as polyolefin-based resins, result in insufficient bonding strength, and existing surface roughening technologies do not achieve sufficient adhesiveness for practical applications.
Innovation Solution
A surface roughening method involving the application of a metal plating layer with a smaller ionization tendency than iron, processing the surface with inorganic acid, and removing the plating layer from the bonding portion to enhance adhesiveness with thermoplastic resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional surface roughening methods (mechanical processing + sulfuric acid dipping) are used on steel members, then the surface roughness is improved, but the bonding strength with thermoplastic resins (especially polyolefin-based resins) remains insufficient
Solution Approach 1:
The invention changes the chemical parameters of the surface treatment by introducing a multi-step process involving oxidation (ferric chloride), sulfuric acid treatment, and amine solution immersion. This transforms the surface chemistry to create functional groups that enhance bonding with diverse resin types, particularly polyolefins
Solution Approach 2:
The invention creates a composite surface structure on the steel member by forming an oxidized layer combined with amine-functionalized groups. This composite surface chemistry provides both mechanical interlocking (from roughness) and chemical bonding (from functional groups), achieving strong adhesion with various thermoplastic resins
2Strength
If aluminum-based, magnesium-based, copper-based, or titanium-based metals are used, then strong adhesiveness with injection molded resins is achieved, but the material selection is limited and cannot include stainless steel with sufficient bonding strength
Solution Approach 1:
The invention changes the surface chemical parameters of stainless steel through oxidation and amine treatment, transforming it from a low-adhesion substrate to a high-adhesion surface that can bond strongly with thermoplastic resins, thereby expanding material selection flexibility
Solution Approach 2:
The oxidized and amine-treated surface layer acts as an intermediary between the stainless steel substrate and the thermoplastic resin. This intermediate layer provides chemical functional groups that facilitate bonding, enabling strong adhesion between the metal and resin interfaces
3Ease of manufacture
If polyolefin-based resins are used due to their low cost and good chemical resistance, then material cost is reduced, but the bonding strength with steel members is significantly deteriorated
Solution Approach 1:
The invention changes the surface parameters of the steel member to be compatible with polyolefin resins by creating a surface with specific chemical functional groups (amine and oxidized groups) that can interact with the non-polar polyolefin chains, enabling strong bonding without sacrificing material cost advantages
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables strong bonding between steel members and thermoplastic resins, improving the bonding strength and adhesiveness for a broad range of resin types, including polyolefin-based resins.
Implementation Method 1
processing the surface of the metal plating layer with inorganic acid
Implementation Method 2
removing the metal plating layer from at least the bonding portion surface
Data Source
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AI summary
A manufacturing method of a metal/resin composite structure of the invention is a manufacturing method for manufacturing a metal/resin composite structure obtained by bonding a steel member and a thermoplastic resin member formed of a thermoplastic resin or a resin composition including the thermoplastic resin, to each other, the method comprising. The manufacturing method of a metal/resin composite structure includes a first step of applying a metal plating layer that is formed of a metal having smaller ionization tendency than ionization tendency of iron and including a roughened surface on a side opposite to a surface to be in contact with the steel member, to at least a bonding portion surface of the steel member to be bonded to the thermoplastic resin member; a second step of processing at least the surface of the metal plating layer with inorganic acid; and a step of molding the thermoplastic resin member and bonding the steel member and the thermoplastic resin member, so that at least a part of the thermoplastic resin member is in contact with the bonding portion surface of the steel member.